Printing apparatus



June 18, 1935. 'E' R NEWCQMB '2,005,046

PRINTING APPARATUS Filed May 19, 1933 INVENTOR. EDH/AED E ,/VEWCOM.

BY WMM/LM) ATTORNEY.

Patented June 18, 1935l PATENT OFFICE PRINTING APPARATUS Edward R. Newcomb, Niagara Falls, N. Y., as-

signor to The Carborundum Company, Niagara Falls, N. Y., a corporation of Pennsylvania ApplieationMay 19, 1933, serial No. 671,850

9 Claims.

This invention relates to a procedure for drying freshly printed webs and to a material useful as an accessory during the drying for supporting the printed web. The invention is particularly applicable to drying of printed material which has a glossy surface, for instance, glazed paper, glassine or cellulose hydrate.

The present invention is an improvement on a known process for drying such freshly printed materials, this known process involving the utilization of a web of granular coated material which is interleaved with a roll of such material after the printing operation has been performed on one surface thereof. The granular coated surface of the web is directed toward the printed surface so that the print will dry satisfactorily without becoming offset. While this process is advantageous, the previously known types of granular coated fabric (such as sandpaper which is'used for woodworking or for metal working) have shown certain disadvantages which have led me to develop a special type of granular coated fabric for use in drying freshly printed materials, such as the ones above mentioned.

The most common type of granular coated fabric is closely coated sandpaper. In this type of fabric, the tendency is for the granules to pile up on each other in a non-uniform manner. Moreover, such paper usually has a heavy coating of sizing, such as glue, which forms roundedA humps. Although use has been made of such paper in connection with the drying of freshly printed material by interleaving the granular coated paper with the printed material, satisfactory results have not been obtained. The rounded humps, by frictional contact with the freshly printed material, tend to cause offsetting rather than to prevent it. Moreover in closely coated sandpaper the granules are frequently so close together that the air circulation is deficient.

In recent years there has come on the market a so-called open-coated paper useful for certain kinds of woodworking because it cuts more rapidly and because it clogs with debris less quickly. In coating this type of abrasive paper the coating is customarily made very open, that is the grains are widely scattered. In utilizing in the drying of printed material the opencoated paper such as just described, the di-fliculty has been that drying takes place too slowly, and moreover there is a tendency for the ink to smear by coming into direct contact with the sheet used as av backing for the grit. This apparently is due to the wide spacing of the granules, since there appears to be a tendency for the printed surface to droop or sag between the granules when the (C1. lOl-420) latter are spaced too far apart. Accordingly, it would seem that when there are not a suicient number of points to properly support a printed surface, the fresh ink comes into contact with the web or backing of the abrasive paper so that the ink beco-mes smeared. 5

One would suppose that it would be possible to use a coarse grit and therefore secure sufficiently numerous supporting y points as well as large volume of air circulation. I have found that if the particles of the grit range in diameter above .2 millimeter (that is, coarser than grit), successful results are not obtained. Even though the coarse particles be so spaced that each grain is in contact with the next, the space between the upper point of each grain and the next grain is so large that proper support of the printed sheet is not provided, with the result that there is sagging or drooping of the printed sheet`between points of support. This sagging or settling of the 'printed sheet between points of support cuts down the effective space for air circulation, so that drying is frequently as slow as with the line and closely coated fabrics. A further disadvantage of the coarser grits is the fact that a heavier backing is required to sustain the coarse grains. Necessarily, the heavier grit mustbe attached to the backing by a heavier glue or adhesive; and it is obvious that the heavier the glue or adhesive, the `less air space there is between the grains. Y

I have found that these difficulties can be overcome, and that offsetting can be reduced to a minimum by employing a granular coated fabric in which the grain size is of the order of magnitude of .05 to .2 millimeter, in which the granular layer is approximately one grain deep, and in which the lateral spacing of the grains is quite limited being regulated in accordance with the grain size.

In order that my invention may be more clearly understood, I will give in detail one specific procedure for obtaining a support of the desired character. A grit is selected, the average dimension of the granules being of. the order of 0.1/20 millimeter, this grain size being that com- 45 monly known as grit. l The granules are a1- lower to fall on a travelling sheet covered with a hardenable adhesive, the amount of grain permitted to fall being carefully regulated so that the granules are closely adjacent to each other 50 `quate air circulation but at the most should not be more than four grain diameters apart. A light paper is used and is given a light coating of glue so that the coated paper is comparatively flexible, and is easily rolled up for a purpose to be described in detail below.

The best results, either with coarse or small granules, are not obtained unless the spacing of the granules on the fabric is made a function of the granule size. The sag or droop of a sheet supported at uniformly distributed points must be small with small granules as the supported sheet is nowhere considerably spaced from the base fabric to which the granules are afxed. The circulation of air between small granules would be reduced practically to a standstill if such granules were crowded as close together as possible, and maximum circulation is obtained by an intermediate arrangement which spaces -the particles lessthan the customary open-coat but more than the close-coat. The circulation of. air between coarse granules is less troublesome than is the case with small granules. Here again it is disadvantageous to space the granules so far apart as to cause the sagging of the sheet to interfere with air circulation. But as larger granules-approaching the upper limiting size of 0.2 millimetercome into use, the lower limit for spacing the granules disappears and the optimum spacing approaches lateral contacting of adjacent granules.

It will be understood therefore that both the size of the granules as well as their distribution are important. The granules should not be smaller than 320 grit (0.05 millimeter diameter) or Ithe air space between the printed material and its support will be insuiiicient for proper circulation of air. The granules should not be larger than 100 grit (0.2 millimeter diameter) for the reasons given above.

As an aid in understanding my invention I have shown diagrammatically in the accompanying drawing the manner in which coiling of the printed web is performed, and the manner in which the granules may be scattered on the fabric used as the support for the printed sheet:

Figure 1 is a vertical sectional view showing diagrammatically a method of printing a sheet and of protecting it during the drying process;

Figure 2 is a plan view on an enlarged scale, illustrating the character of the grain spacing on my improved granular coated fabric;

Figure 3 is a sectional view on the line III- III of Figure 2;

Figure 4 is a diagrammatic sectional view on a much enlarged scale showing the manner in which large grains support the printed sheet; and

Figure 5 is a similar diagrammatic view in which small grains support the printed sheet.

Referring to the drawing in detail, a web or sheet 2 of non-absorbent material is drawn from a supply roll 3 between a printing roll 4 and a counter roll 5. Ink is supplied to the type on the cylinder 4 from means denoted by the reference character 6. The freshly printed sheet 2 is then rolled on a cylinder 1 along with a granular coated sheet 8, the rough side of the sheet 8 being adjacent to the freshly printed side of the nonabsorbent sheet 2. 'Ihe sheets 2 and 8 are left rolled up on the support 1 until the ink has dried.

I have found that satisfactory results in drying a freshly printed sheet of non-absorbent material can not be obtained unless the grit size is no coarser than grit and no finer than 320 grit.

100 grit corresponds to about .2 millimeter and 320 grit corresponds to about .05v millimeter.

Grits intermediate these two extremes may be employed and satisfactory results obtained. I have found that particularly goodvresults are obtained with grit which has a diameter of grain of about .127 millimeter.

In Figures 2 and 3 is shown a sheet of base fabric I0 by which it is intended to include paper, cloth, or other material used in 4the abrasive art in an equivalent capacity, which carries granules I I, scattered over the sheet Ill in such manner as to prevent superposing of one` grain on top of another. As is apparent from Fig. 3, the grain surface varies not more than one grain diameter from the average surface elevation. 'Ihis is important because, as shown in .Figures 4 and 5 the grains are intended to support a freshly printed web 2 during drying, as illustrated at 1 in Figure 1. The granules I I are affixed to the fabric I IJ by being embedded in a coating or layer of glue I2 on the fabric. For coarser granules such as shown in Figure 4, a heavier coating of glue I2 and a stouter, heavier base fabric I0 are required.

The permissible sag of the web 2 is less than the diameter h1 in the case of the granules shown in Figure 4 and h2 in the case of the granules shown in Figure 5 because in each case the thickness of the layer of glue I2 must be subtracted. The spacing s1 of the particles shown in Figure 4 should be small enough so that even when rolled up in the coil, the web 2 will not be pushed down in between points of support so as to smear the fresh print and also cut olf air circulation. The spacing s2 of the particles shown in Figure 5 should be large enough to afford the necessary freedom for air circulation; but in no case should it be more than 4 grain diameters, if a suil'lcient number of supporting points are to be provided. If care is taken in the distribution of the grain so that in no case does the grain surface vary more than one grain diameter from the average surface elevation, uniformity of results is obtained. It is thus apparent that the effectiveness ofthe granular coated fabric in reducing offset, and in general the protection of the printed sheet during the critical drying operation depends on the proper selection of grit size together with the proper spacing of the granules.

I attribute my improved results partly to the increased space for air circulation and partly to the large number of supporting points afforded by the arrangement of grains provided by my invention. I have furthermore found that advantageous results follow from the reduction in the weight and thickness of the granular coated paper. The thinner the granular coated paper, the smaller and lighter is the roll into which the printed material is coiled to be dried.

It will be understood that the abrasive quality of the granular coating is dormant in the process of supporting a fabric which I have disclosed. Accordingly, materials such as sand, or various artificial abrasive materials may be selected without thought for their abrasive quality.

While I have illustrated anddescribed certain preferred embodiments which my invention may assume, it will be understood -that my invention is not limited to the specific details of the examples given but may be otherwise practiced within the scope of the following claims.

I claim:

1. A printing accessory comprising a granular coated fabric in which the grain size is of the order of magnitude of .05 to .2 millimeter and in which the granular layer is approximately one grain deep while the lateral spaces/between the grains are less than 4 grain diameters.

2. A printing accessory for supporting a freshly printed non-absorbent sheet during the drying process comprising a granular coated fabric havinga single layer of grain of average diameter of about 0.13 millimeter and distributed so. that the lateral spaces are less than 4 grain diameters.

3. A printing accessory comprising a granular coated fabric in which the grain size is of the order of magnitude of .2 millimeter and in which the grains are disposed in a single layer with the grains substantially in lateral contact.

4. A printing accessory comprising a granular coated fabric in which the grain size is of the order of magnitude of .05 millimeter in diameter and in which the granular layer is approximately one grain deep while the lateral spaces between the grains are 4 grain diameters.

5. A printing accessory comprising a granular coated fabric in which the grain size is uniform and of the order of magnitude of .05 to .2 millimeter and in which the granular layer is approximately one grain deep while the lateral spaces between the grains are uniform and less than 4 grain diameters.

6. A printing accessory comprising a granular coated fabric in which the grain size is uniform and of the order of magnitude of 0.13 millimeter and in which the granular layer is approximately one grain deep while the lateral spaces between the grains are uniform and less than 4 grain diameters.

7. A printing accessory comprising a granular coated fabric in which the grain size is uniform and of the order of magnitude of .2 millimeter and in which the grains are disposed in a single layer with the grains substantially in lateral contact.

8. A printing accessory for supporting a freshly printed sheet during the drying process, comprising a granular coated flexible sheet having a coating layer of grain of a size of the onder of magnitude of .05 lto .2 millimeter diameter, said coating layer being intermediate in weight between that of open coat and that of close coat abrasive sheets.

9. A printing accessory for supporting a freshly printed sheet during the drying process, comprising a granular coated flexible sheet having a coating layer of grain of a size of the orderl of magnitude of .05 to .2 millimeter diameter, said coating layer being materially lighter than that of close coat abrasive sheets 'and having an average lateral spacing between the grains of less than 4 grain diameters.

EDWARD R. NEWCOMB. 

